This invention relates to hydantoin esters, and particularly methylolated hydantoin fatty acid ester compounds, having surfactant and biocidal properties, and usable in solutions, emulsions and dispersions, e.g. forming personal care, household, and industrial product, formulations.
All percentages (%), parts (pts) or proportions set forth herein are by weight unless specifically indicated otherwise.
Hydantoin, or 2,4-imidazolidinedione [i.e., 1,3-diazacyclopentane-2,4-dione], is a compound of the formula ##STR1## that has two active nuclear nitrogen atoms, i.e., an amide nitrogen at the 1-position and an imide nitrogen at the 3-position, per the bracketed naming system, both of which can be used to form derivatives.
One type of hydantoin compounds includes those based on the dimethyl derivative: dimethylhydantoin [i.e., 5,5-dimethyl-1,3-diazacyclopentane-2,4-dione], or simply DMH, of the formula ##STR2##
The corresponding methylolated hydantoins are biocides used in cosmetic preparations. They include the monomethylolated derivative: monomethylolated dimethylhydantoin [i.e., 1-hydroxymethyl-5,5-dimethyl-1,3-diazacyclopentane-2,4-dione], or simply MDMH, of the formula ##STR3## and the dimethylolated derivative: dimethylolated dimethylhydantoin [i.e., 1,3-dihydroxymethyl-5,5-dimethyl-1,3-diazacyclopentane-2,4-dione], or simply DMDMH, of the formula ##STR4##
The dimethylolated hydantoin derivative DMDMH (iv) is effective as a formaldehyde donor at a minimum inhibitory concentration (MIC) of 0.1%. The monomethylolated hydantoin derivative MDMH (iii) is effective at 0.2% MIC, as its biocidal activity is half that of the dimethylolated derivative DMDMH (iv), since it can donate only half as much formaldehyde (traceable to the hydroxymethyl group) per molecule.
Other known hydantoin derivatives are the polyethoxylated hydantoin esters: di(polyethoxylated) dimethylhydantoin esters [i.e., 1,3-di(polyethylene oxide)-5,5-dimethyl-1,3-diazacyclopentane-2,4-diones), or simply DEOXDMH esters, of the formula ##STR5## wherein m and n are 5-15, Z is H or --C(O)R, and R is the aliphatic group of a fatty acid radical. The DEOXDMH esters (v) are emulsifiers, e.g. used in the textile industry for fiber finishing applications, and are not biocidal formaldehyde donors.
Aside from the MDMH (iii) and DMDMH (iv) biocides, and DEOXDMH ester (v) emulsifiers, the literature only appears to disclose hydantoin esters of radically different structure, used as ultraviolet (UV) absorbers or for medical or other remote purposes. As to lipophilic molecules having biocidal activity, certain fatty acids are known to have such activity in addition to surfactancy, but these do not involve hydrantoin based molecules. Those instances of esters that perform as a bifunctional surfactant/biocide are mostly concerned with glycerol esters.
Common cosmetic preservatives are DMDMH (iv), Quaternium 15 (Dowicil 200, a trademark of Dow Chemical Co.), imidazolidinyl urea (Germall 115, a trademark of Sutton Laboratories), parabens [alkyl-hydroxybenzoates], phenols [alkylphenol], phenoxyethanol, isothiazolinones, fatty acids, monoglycerol esters, formaldehyde and 2-bromo-2-nitropropane-1,3-diol.
Formaldehyde donor biocides are effective against bacteria, and to a lesser extent against molds or yeast, in cosmetic or health care preparations, e.g. shampoos, hair rinses, creams, soft soaps, etc. In such preparations, surface active biocides are effective against molds and yeast, and to a lesser extent against bacteria, their antimicrobial activity against these organisms tending to increase markedly with increase in their lipophilic, e.g. alkyl, chain, up to a specific length.
Generally, to provide the cosmetic formulation with a broad spectrum preservative system against all organisms, i.e., of the bacteria, mold, and yeast, groups, a multiple number of biocides, each specifically effective against a given group, are combined.
U.S. Pat. No. 4,844,891 teaches a synergistic combination of biocides as a broad spectrum preservative system for a wide variety of product formulations.
It would be desirable to have a compound that combines the attributes of an effective biocide and a surface active agent in one molecule, forming a stable product, e.g. usable in cosmetic formulations, that can be synthesized in quantitative yield by a simple process, and that reduces the inventory that would otherwise require two or more compounds for such purposes.